1. Field of the Invention
The present invention relates to a technique for saving the battery of, for example, a game machine for home use, as well as to a portable game machine.
More particularly, the present invention relates to a portable game machine having a function of monitoring and managing power consumption of a battery in order to diminish the frequency of replacement of the battery.
2. Related Art
In a game machine, memory (ROM or RAM) incorporated in the game machine or memory (cassette ROM) provided within a game cassette is accessed in accordance with the execution progress of a game, thereby reading data from or writing data into the memory.
At the time of access to memory, an address specified by an address signal is accessed. In order to enable access to a desired address, an address signal is switched at each access timing. In a common game machine, an address signal is switched in internal memory in completely the same manner as in external memory.
Data are written or read in response to a write or read signal. In a common game machine, a read signal and a write signal are input to internal memory in completely the same manner as for external memory.
Switching of an address signal involves consumption of a battery. If an address signal is switched in external memory even at the time of access to internal memory, which would originally be accessed independently, battery power is wasted.
If a write signal is input not only to internal memory but also to external memory at the time of data being written into the internal memory (in a case where an address signal represents an address of internal memory), data to be written into the internal memory would be transmitted to the external memory, thereby resulting in a problem of generation of unwanted data (garbage).
Most current portable game machines are activated by dry cells, such as alkaline dry cells or manganese dry cells. Power is supplied to the game machine from the dry cells while the player is playing a game. When the player terminates the play of the game, power supplied from the cells is stopped.
In a portable game machine, ability to resume a game is secured. Even when a game is temporarily suspended and the power of the game machine is turned off, the game can be resumed from where the player had left off.
In order to ensure such an ability to continue a game, a voltage is continuously applied to a CPU or memory of the portable game machine at all times. To this end, in addition to having a drive battery used when the player plays a game, such as alkaline dry cells or manganese dry cells, the game machine is further equipped with a dedicated battery, such as a coin-type battery.
Most current and widely-accepted portable game machines are equipped with a function other than a game, such as a clock function. The reason why such an additional function, like a clock function, remains properly activated even while the power of the game machine is turned off is that the function is appropriately controlled by means of the dedicated battery, such as a coin-type battery, even when the power of the game machine is turned off.
As mentioned above, the current portable game machine has a drive battery for providing high power for activating a liquid crystal display device or a speaker during the play of a game, and a control battery for providing lower power for the CPU or the additional function while the game machine remains deactivated. Manganese dry cells or alkaline dry cells are employed as a typical drive battery, and a coin-type battery, such as a mercury battery or a lithium battery, is employed as a typical control battery.
Under such circumstances, the battery poses a problem in terms of its life. A voltage is continuously applied to the CPU and memory of the portable game machine in order to ensure the ability to continue a game, and power is continuously applied in order to control the additional function, such as a clock function. As a result, the battery becomes depleted more and more, so that the battery must be replaced frequently.
However, replacement of a battery, particularly a coin-type battery, involves troublesome labor. Further, the coin-type battery is more expensive than manganese or alkaline dry cells. Therefore, the number of times a battery is to be replaced is desirably minimized.
In contrast, if the player has great concern about only power saving and has continuously used a battery which is incapable of supplying a voltage sufficient for controlling the game machine, a difficulty is encountered in reliably supplying an appropriate amount of power at an appropriate voltage, so that the player may encounter a serious trouble problem such a loss of scores which have been achieved thus far.
The present invention has been conceived in view of the problem, and the foregoing object of the present invention is to provide a game machine capable of saving power of a battery thereof by elimination of unwanted switching between address signals, as well as to provide an access control method for use with the game machine.
To this end, the present invention provides a technique related to a game machine which exchanges (sends/receives) data with the outside in accordance with the execution progress of a game. The technique is characterized in that the an address signal is switched only at the time of access to the outside, thereby outputting a read signal or a write signal. In general, a request for access to external memory is made less frequently than is a request for access to internal memory. Therefore, if the present invention is applied to such a game machine, a highly advantageous effect is considered to be yielded.
More specifically, the following inventions are provided:
(A) A game machine which sends/receives data according to the execution progress of a game, comprising:
an access control circuit which controls access made by a the control circuit.
(B) The game machine as defined in (A), wherein the access control circuit varies a control signal by changing the access signal when the control circuit makes access to another circuit; i.e., a circuit other than the control circuit.
(C) A game machine which sends/receives data according to the execution progress of a game, comprising:
an access control circuit including
a latch circuit which latches an access signal, changes the access signal and outputs the thus-changed access signal when the control circuit accesses another circuit; i.e., a circuit other than the control circuit, and holds the access signal and outputs the thus-held access signal in a case other than the case where the control circuit accesses another circuit; and
a control signal output circuit which outputs a desired control signal when the control circuit accesses another circuit; i.e., a circuit other than the control circuit.
(D) An access control method for use with a game machine which sends/receives data according to the execution progress of a game, the method comprising a step of:
varying an access signal by changing a control signal only when a control circuit accesses another circuit; i.e., a circuit other than the control circuit.
In the game machine of the present invention as described in (A) through (D), a control signal is changed by means of switching an access signal at the time of a control circuit accessing another circuit; i.e., a circuit other than the control circuit. Accordingly, needless switching between access signals is eliminated, thus saving power of the battery of the game machine and preventing generation of garbage, to thereby effect efficient processing.
Since there can be diminished the number of times switching between address signals is effected, the present invention yields an advantage of the ability to diminish undesired radiation of electromagnetic radio waves or noise.
 less than Device greater than 
A term xe2x80x9cgame machinexe2x80x9d signifies a game machine for home use or a portable game machine.
Throughout the specification, a term xe2x80x9caccess control circuitxe2x80x9d signifies a circuit xe2x80x9cwhich controls access which a control circuit makes with respect to another circuit; i.e., a circuit other than the control circuit, and temporarily retains an access signal output from the control circuit.xe2x80x9d Accordingly, the access control circuit is not limited to a circuit having a configuration such as that described in the section entitled xe2x80x9cModes for Carrying Out the Invention.xe2x80x9d Any circuit maybe employed as the access control circuit, so long as the circuit has a function identical with that set forth.
 less than Access Control Circuit greater than 
A term xe2x80x9ccontrol circuitxe2x80x9d signifies a computing circuit. A termxe2x80x9canother circuit; i.e., a circuit other than a control circuitxe2x80x9d signifies a circuit, an element, or a like member which is to be incorporated in a game machine, such as ROM or RAM to be incorporated in the game machine, as well as a circuit, an element, and a like member which is to be handled separately from a main unit of the game machine, such as cassette ROM incorporated in a game cassette.
A term xe2x80x9caccess signalxe2x80x9d signifies a signal (for example, an address signal) for instructing the control circuit to make an access, and a term xe2x80x9ccontrol signalxe2x80x9d signifies a signal for controlling functions of the game machine (for example, a read signal, a write signal, or a chip select signal).
An expression xe2x80x9cswitching between access signalsxe2x80x9d signifies that an access signal, which has been previously input to the access control circuit, is switched to another newly-input access signal. An expression xe2x80x9clatching of an access signalxe2x80x9d signifies that an access signal, which has been previously input to the access control circuit, is latched, in its present form, even when another access signal is newly input to the access control circuit.
An expression xe2x80x9cchanging of a control signalxe2x80x9d signifies a change in the output status of a control signal; for example, from a low state; to a high state or vice versa.
The present invention has been conceived to solve the previously-described problem, and the object of the present invention is to provide a battery power monitoring and management system capable of diminishing the number of times a battery is to be replaced while ensuring reliable supply of.an appropriate amount of power at a suitable voltage to a portable game machine having a drive battery, such as a manganese cell or an alkaline cell, and a control battery, such as a coin-type battery.
To achieve the foregoing object, in the present invention, a drive battery and a control battery in principle provide compensation for each other. Therefore, in the event of occurrence of anomalous conditions or depletion of power, prevention of depletion of the control battery is prioritized, thereby saving the power of the control battery.
Simultaneously, in the present invention, a control battery whose power supply is appropriately saved is used for performing other useful control operations.
More specifically, the present invention provides the following inventions.
First, a portable game machine of the present invention
(E) A portable game machine comprising:
a game drive circuit for activating a game;
a game control circuit for issuing a control signal for activating a game;
a high-power short-life first power supply serving as a battery for activating the game drive circuit and the game control circuit; and
a low-power long-life second power supply serving as a battery for activating the game drive circuit and the game control circuit;
the portable game machine further comprising:
a power switch for turning on or off power supply to the game drive circuit from the first power supply; and
a power management system for controlling a power supply channel from the first power supply and a power supply channel from the second power supply, the power management system having, the function of performing control operation (i) indispensably and at least one control operation selected from the group consisting of (ii), (iii), (iv), and (v):
(i) an operation for, in principle, supplying power to the game drive circuit from the first power supply, as well as for supplying power: to the game control circuit from the first power supply when the first power supply has sufficient power supply ability and supplementally supplying power from the second power supply;
(ii) an operation for supplying power to the game control circuit from the first power supply, when it is detected that the power supply capability of the second power supply has dropped to a predetermined level or lower;
(iii) an operation for preventing power supply to the game control circuit from the second power supply even though the power switch is turned on, when it is detected that the power supply capability of the first power supply has dropped to a predetermined level or lower;
(iv) an operation for preventing power supply to the game drive circuit from the first power supply without involvement of power supply to the game control circuit from the second power supply when it is detected that the power supply capability of the first power supply has dropped to a predetermined level or lower, as well as for preventing power supply to the game control circuit from.the second power supply even though the power switch is turned on; and
(v) an operation for supplying power supply to the game drive circuit from the first power supply when runaway of a control circuit provided within circuitry is detected.
A term xe2x80x9cfirst power supplyxe2x80x9d corresponds to the drive battery, and a term xe2x80x9csecond power; supplyxe2x80x9d corresponds to the control battery. By means of such a configuration, when the control battery becomes depleted, power is supplied from the drive battery to a game control circuit. The status of a game, as has been accumulated thus far, such as a stage, an empirical value, and a score, is reserved unless the player removes the first and second power supplies simultaneously [this can be prevented by forming a section for storing a coin-type battery (i.e., the second power supply) so as to make removal of the coin-type battery (the second power supply) difficult (through use of, for example, a simple cover which cannot be removed manually without use of a tool of some kind)].
In contrast, in the event of depletion of the drive battery, no power is supplied to the drive battery from the control battery, thereby preventing depletion of the control battery and conserving ability to supply power to the control battery.
In the event that the drive battery (dry cells, such as manganese dry cells or alkaline dry cells) are abruptly removed from the game machine, power will not be supplied to the drive circuit from the control battery. Accordingly, depletion of the control battery is prevented, and the ability of the control battery to supply power is conserved.
Next, the second characteristic of the portable game machine of the present invention resides in comprising the following elements solely or in combination:
(F) The portable game machine as defined in (E), further comprising the following device or functions solely or in combination:
(i) a battery depletion indicator which indicates a drop in, the power supply capability of the first power supply and/or a drop in the power supply capability of the second power supply and whose indication differs according to whether a drop in the power supply capability of the first power supply is indicated or a drop in the power supply capability of the second power supply is indicated;
(ii) a clear-off function of shutting off power supply to a game drive circuit from the first power supply after formation of a screen appearing after shut-off of power; and
(iii) a shut-off function for shutting off a control mechanism pertaining to control of the game control circuit with reference to the processing required until the game has reached a good point in time for leaving off, in terms of game control.
By virtue of the first and second characteristics of the present invention, in the event that operation of a CPU has become anomalous as a result of abrupt removal of, for example, a memory cassette having a game program stored therein, power supply from the drive battery is shut off. Subsequently, after the game has reached a good point in time for leaving off, a game-control-related mechanism of the control circuit is turned off, thereby preventing depletion of the drive and control batteries, which would otherwise be caused when operation of the CPU has become anomalous.
Further, the present invention also provides a portable game machine which employs the following elements solely or in combination.
(G) A portable game machine comprising:
a game drive circuit for activating a game;
a game control circuit for issuing a control signal for activating a game;
a high-power short-life first power supply serving as a battery for activating the game drive circuit and the game control circuit; and
a low-power long-life second power supply serving as a battery for activating the game drive circuit and the game control circuit, the portable game machine comprising the following device or functions solely or in combination:
(i) a battery depletion indicator which indicates a drop in the power supply capability of the first power supply and/or a drop in the power supply capability of the second power supply and whose indication differs according to whether a drop in the power supply capability of the first power supply is indicated or a drop in the power supply capability of the second power supply is indicated;
(ii) a clear-off function of shutting off power supply to a game drive circuit from the first power supply after formation of a screen appearing after shut-off of power; and
(iii) an automatic shut-off function for shutting off a control mechanism pertaining to control of the game control circuit after power supply to the game drive circuit from the first power supply has been cut off, with reference to the processing required until the game has reached a good point in time for leaving off, in terms of game control.
In a portable game machine of the present invention having the previously-described second characteristic, a battery-depletion indicator preferably provides an indication by means of blinking of a lamp. In this case, the speed at which the battery-depletion indicator blinks differs according to whether the power supply capability of the first power supply is degraded or the power supply capability of the second power supply is degraded. In the event of a battery being depleted, the player can readily ascertain whether the first battery or the second battery is depleted.
In the portable game machine of the present invention, xe2x80x9cformation of a screen after shutoff of power supplyxe2x80x9d is effected when power supply to a game drive circuit from the first power supply is shut off. In a case where a liquid crystal display screen is adopted as a game screen, power supply to the game screen drive circuit is shut off after the entire game screen has been made white in the case of the liquid crystal display screen being of normally white type or after the entire game screen has been made black in the case of the liquid crystal display screen being of normally black type. As a result, there can be prevented a transient phenomenon, such as screen flickers, which would otherwise be caused when the liquid crystal drive circuit is abruptly turned off, thereby preventing a screen from disappearing unfavorably.
A power management system of the present invention will be conceptually expressed as follows:
(H) A method of controlling a power supply channel within a game machine, in which
in a case where two or more power supply channels are present, a power supply channel relating to a control circuit is prioritized over a power supply channel relating to a drive circuit, and in the event of occurrence of a shortage in supply power in either of the power supply channels, power supply to the power supply channel relating to the control circuit is maintained to the end.
A CPU is very vulnerable to fluctuations in voltage. If a voltage within a range between activation and deactivation is applied to the CPU, the CPU forms an erroneous determination as to whether to be activated or to be deactivated, thereby causing faulty operations. The portable game machine equipped with the power management system of the present invention diminishes depletion of the control battery (the second power supply) to as little as possible, thus minimizing the chance of application to the CPU of such a misleading voltage (within the range between activation of a CPU or deactivation of a CPU).
In the portable game machine equipped with the power management system of the present invention, in the event that the control battery (the second power supply) becomes depleted and the voltage supplied from the control battery has dropped to such a voltage (i.e., a voltage within the range between activation of a CPU and deactivation of a CPU), the player is unfailingly informed of battery depletion and is prompted to replace the control battery.
Further, in the game machine equipped with the power management system of the present invention, in the event of certain occurrence, such as abrupt removal of dry cells during the play of a game or abrupt removal of a memory cassette having a game program stored therein, the game machine is prevented from being broken, thereby conserving game results which have been achieved thus far (the status of a game; for example, a stage, an empirical value, history, and a score, all having been achieved by the player through his great efforts).
Moreover, effective saving of battery power contributes to safeguarding of the environment, as well as to energy conservation.
In another aspect of the present invention, there is provided a portable game machine as provided below.
(I) A portable game machine comprising:
a game drive circuit for activating a game;
a game control circuit for issuing a control signal for activating a game;
a high-power short-life first power supply serving as a battery for activating the game drive circuit and the game control circuit;
a low-power long-life second power supply serving as a battery for activating the game drive circuit and the game control circuit; and
a power management system for controlling a power supply channel from the first power supply and a power supply channel from the second power supply, in which
when it is detected that the power supply capability of the first power supply is lower than a predetermined level, the power management system shuts off power supply in ascending sequence of priority from a low priority level in accordance with pre-set priority levels.
With regard to a term xe2x80x9cpriority,xe2x80x9d circuits, which are selected from primarily a drive circuit, are prioritized arbitrarily. Priority assigned to circuits is determined, as required, in comprehensive consideration of the power dissipation of a circuit of interest.
The following recording medium can also be used in fulfilling the present invention.
(J) A computer-readable storage medium on which there is stored a program for performing control operation (i) indispensably and at least one control operation selected from the group consisting of (ii), (iii), (iv), and (v):
(i) an operation for, in principle, supplying power to the game drive circuit from the first power supply, as well as for supplying power to the game control circuit from the first power supply when the first power supply has sufficient power supply ability and supplementally supplying power from the second power supply;
(ii) an operation for supplying power to the game control circuit from the first power supply, when it is detected that the power supply capability of the second power supply has dropped to a predetermined level or lower;
(iii) an operation for preventing power supply to the game control circuit from the second power supply even though the power switch is turned on, when it is detected that the power supply capability of the first power supply has dropped to a predetermined level or lower;
(iv) an operation for preventing power supply to the game drive circuit from the first power supply without involvement of power supply to the game control circuit from the second power supply when it is detected that the power supply capability of the first power; supply has dropped to a predetermined level or lower, as well as for preventing power supply to the game control circuit from the second power supply even though the power switch is turned on; and
(v) an operation for supplying power supply to the game drive circuit from the first power supply when runaway of a control circuit provided within circuitry is detected.
(K) The computer-readable storage medium as defined in (J), wherein there is stored a program for selectively fulfilling processing relating to each of the following device or functions:
(i) a battery depletion indicator which indicates a drop in the power supply capability of the first power supply and/or a drop in the power supply capability of the second power supply and whose indication differs according to whether a drop in the power supply capability of the first power supply is indicated or a drop in the power supply capability of the second power supply is indicated;
(ii) a clear-off function of shutting off power supply to a game drive circuit from the first power supply after formation of a screen appearing after shut-off of power; and
(iii) a shut-off function for shutting off a control mechanism pertaining to control of the game control circuit with reference to the processing required until the game has reached a good point in time for leaving off, in terms of game control.
Such a program enables provision of a portable game machine which, partially shuts off power supply according to a decrease in the power supply capability (for instance, depletion of a battery) of a portable power source (basically corresponding to a battery)
The power management system of the present invention will be described as follows from another viewpoint.
(L) A game machine comprising:
a display (LCD) for rendering a game image;
game program memory (memory) for storing a game program; a controller (CPU) for controlling individual functions of the game machine; and
two power circuits including a drive power circuit and a back-up power circuit (see FIG. 11).
In the power management system of the present invention the drive power circuit supplying power to the display, the game program memory, and a CPU; and the back-up power circuit supplying power to the CPU.
The power management system of the present invention can be embodied by means of, for example, the following circuit configuration (the circuit configuration will be described in detail later).
(M) A portable game machine including:
a game drive circuit for activating a game;
a game control circuit for issuing a control signal for activating a game;
a high-power short-life first power supply serving as a battery for activating the game drive circuit and the game control circuit; and
a low-power long-life second power supply serving as a battery for activating the game drive circuit and the game control circuit, the game control circuit being connected to the first and second power-supplies, the-game machine further comprising:
a capacitor which is recharged by the first power supply;
a comparator circuit which determines a difference between an output from the capacitor and an output from the first power supply and is activated when the difference has exceeded a predetermined value; and
a switch circuit which turns on or off power supply to the game drive circuit from the first and second power supplies and shuts off the power supply to the game drive circuit from the first and second power supplies when the comparator circuit is turned on.
(N) A portable game machine including:
a game control circuit for issuing a control signal for activating a game;
a high-power short-life first power supply serving as a battery for activating the game drive circuit and the game control circuit; and
a low-power long-life second power supply serving as a battery for activating the game drive circuit and the game control circuit, the game control circuit being connected to the first and second power supplies, the game machine further comprising:
a comparator circuit which determines a difference between an output from the first power supply and an output from the second power supply and is activated when the difference has exceeded a predetermined value; and
a switch circuit which turns on or off power supply to the game drive circuit from the first and second power supplies and shuts off the power supply to the game drive circuit from the first and second power supplies when the comparator circuit is turned on.
The portable game machine of the present invention, which has been described above, is equipped with a drive battery and a control battery. An appropriate amount of power is ensured at a suitable voltage, and the frequency of replacement of dry cells can be diminished